Alismobates piratus, Pfingstl & Bardel-Kahr & Schäffer, 2023

Pfingstl, Tobias, Bardel-Kahr, Iris & Schäffer, Sylvia, 2023, The Caribbean intertidal mite Alismobates inexpectatus (Acari, Oribatida), an unexpected case of cryptic diversity?, Organisms Diversity & Evolution 23 (4), pp. 811-832 : 816-818

Alismobates piratus sp. nov. urn:lsid:zoobank.org:act:

35A22D71-5078-4D1A-AA61-A6DCD5A8E7E5.

Type material: Holotype male (size 356 µm x 240 µm), Curaçao: Boca Ascención (CU_15) Bostrychia on rocks in the upper eulittoral area, 5 Feb. 2016; paratype (1 female 375 µm x 249 µm) same data as for holotype, both types deposited in the Senckenberg Museum für Naturkunde Görlitz ( SMNG).

Etymology: The species occurs in the Caribbean area which is well known for its long historical era of piracy. The specific epithet ‘ piratus’ refers to the Latin word for pirate (‘pirata’) and is given as noun in apposition.

Species diagnosis: Dark brown sclerotized mites. Average length 362 μm, mean width 233 μm. Notogaster oval in shape. No conspicuous sexual dimorphism; there is only the common sexual dimorphism in overall body size, with is proportional to its frequency, the number of mutations is indicated as hatch marks. Small black circles represent intermediate haplotypes not present in the dataset. Colors refer to different sample locations grey shades represent the different species females being generally slightly larger. Van der Hammen’s Organ well developed, typical for the genus. Sensillum clavate, spinose. One pair of large cuticular ridges in position of prodorsal lamellae. Interlamellar setae minute. Lenticulus (light spot) large, variable in shape and with irregular borders. Areas flanking lenticulus conspicuously granular. Fourteen pairs of short and simple, notogastral setae, associated with small porose areas. Epimeral setation 3–1-2–2. Four pairs of genital setae. One pair of aggenital setae. Three pairs of adanal setae. Two pairs of anal setae. Legs monodactylous with large claw. Porose areas on trochanters III and IV and all femora. Leg setation (chaetome, solenidia): Leg I 0–4-2–3-18, 1–2-2; leg II 0–4-2–3-15, 1–1-1; leg III 1–3-1–3-15, 1–1-0; leg IV 1–2-2–3-12, 0–1-0.

Diagnostic nucleotides (only unique diagnostic characters are given): In COI, position 7 is occupied by base G, position 17 by base T, position 19 by base A, position 73 by base T, position 82 by base C, position 133 by base T, circles represent intermediate haplotypes not present in the dataset. Colors refer to different locations as indicated on the respective map. a) New Providence Island, Bahamas. b) Bermuda position 199 by base T, position 340 by base A, position 346 by base A, position 391 by base G, position 409 by base C, position 538 by base C, position 551 by base G, position 574 by base C, position 608 by base C and position 613 by base T.

In 18S rRNA, position 728 is occupied by base G, position 768 by base A and position 1350 by base A.

Distribution: Presently, Alismobates piratus sp. n. is known to show a distribution range from Hispanola to the Lesser Antilles. There are reports from the Lesser Antillean islands of Guadeloupe, Barbados and Curaçao, and there is a record from the northeastern coast of the Dominican Republic, namely from shores of the Samaná Peninsula (see Fig. 2 ). Distributions on Barbados and the Dominican Republic coincide with occurrences of A. inexpectatus whereas specimens of both species were found syntopically (in a single sample of ca. 10cm 2 algae) on the coast of Samaná.

Remarks: The new species A. piratus sp. nov. is morphologically identical to A. inexpectatus ( Fig. 6 ) and thus cannot be distinguished from it based on microscopic investigation only.

The lengths and shapes of certain characters, i.e. sensillum and body setae, may look slightly different in some of our depictions, but these are results of slightly different observational perspectives or of different orientations of these characters. These structures are bendable and they are inserted on a convex surface, therefore a slightly different viewing angle may result in a divergent appearance. For these reasons, it is also extremely difficult to make standardized measurements of these traits. However, we observed more than 270 specimens under the microscope and could not find any reliable diagnostic character separating the two species (to the best of our knowledge), therefore, we herein provide the species diagnosis only, which is also valid for A. inexpectatus ; a detailed description applying to both species is given in Pfingstl and Schuster (2012). Due to the identical phenotypes, species determination should always include the analysis of molecular genetic markers.

Figures

Fig. 2 Map showing records of the two Alismobates species in the Caribbean and TCS haplotype network based on their COI sequences. Light red arrows on map indicate ocean currents and their directions. Each circle in the network corresponds to one haplotype and its size

Fig. 6 Dorsal (left) and ventral (right) depictions (legs omitted or only partially drawn) of the two genetically distinct Alismobates species, illustrating the phenotypic similarity. a) A. piratus sp. n. (specimen from Barbados BA_22); b) A. inexpectatus (specimen from the Dominican Republic DR_03)